Abstract: To investigate the gas-solid flow characteristics in an ultra-high riser, the upper 20m of the original 60-meter-high cold CFB riser of the 600MW supercritical circulating fluidized bed boiler in the Sichuan Baima power plant, was changed into a rectangular cross section riser. It was focused on illustrating the impacts of the fluidizing velocity on the axial/section distribution of particle concentration and diameter in the upper riser. The experimental results indicated that the distribution of particle concentration and diameter was closely correlated with fluidizing velocity and geometric structure. At a certain initial height of bed materials, the void fraction at the top of the riser stayed uniform, then decreased along the axial direction, and finally appeared an inverted C-shape distribution with the increase of fluidizing velocity. Moreover, a non-uniform section distribution of particle concentration was observed at high fluidizing velocity, where the particle concentration was obviously larger near the short side than that near the long side. Besides, the average particle diameter increased with the fluidizing velocity, and distributed uniformly along the section. However, the particle diameter decreased slightly along the height direction and was slightly smaller near the short side than that near the long side in the upper riser.

Key words: circulating fluidized bed, particle concentration, particle diameter, fluidizing velocity

摘要： 为研究超高提升管内的气固流动特性，依托四川白马电厂600MW超临界循环流化床锅炉现有钢架，将原有60m高的提升管冷模试验台的上部20m改为矩形截面的循环流化床提升管试验台。本文重点研究了提升管流化风速对上部颗粒浓度的轴向/截面分布特性及其影响因素。试验结果表明：颗粒浓度和颗粒粒径的分布特性与流化风速和几何结构密切相关，在一定初始床料高度下，随着风速的增加，提升管上部的空隙率沿轴向先不变然后减少，并最终呈现倒C形分布；截面浓度从均匀分布逐渐变为近短边壁处的颗粒浓度要明显大于近长边壁处的不均匀分布；平均颗粒粒径则随风速的增加而增大，沿截面分布均匀，但是沿提升管高度方向平均颗粒粒径沿轴向会略微减小，且提升管上部近短边壁的颗粒粒径要稍小于近长边壁的。

关键词: 循环流化床, 物料浓度, 颗粒粒径, 流化风速